If memory serves correct, I first read about using glycerin in Joel Friels book, but my memory is... ...what were we talking about?

It basically makes you retain water, so that you are "superhydrated" for an effort in hotter conditions. Hammer adds a raspberry flavor as well as L-carnitine (sp) for whatever reason you could find on their website/literature.

I am preloading it for the KTR, just to see what the effects are. The taste is minimal, so that is a non-factor. I will not use it during the race, just to pre-hydrate. You use 1 tbsp per 100lbs body weight three times per day for three days prior to the event. Testimonials have indicated that they used it during an event, but that is not how it is advised per the instructions.

I have not done the KTR before, so I will not be able to compare. I may come back to comment on my findings, should I not want to hide with my tail between my legs for not having finished...

I've used it a couple of times and I'm not really sure it was doing anything but it wasn't very hot and I wasn't sweating much anyway. I'm going to continue to use it as it gets hotter here in Virginia to see if it works.

Well I managed to make it, so I guess I will offer something. That something is that I don't know if it worked, but hydration was never an issue. The direction this year was such that you could get in trouble with water, but much less so than my understanding and deductive reasoning about last year's direction. I was able to get to the 1/2 way point using 5 liters of hydration bladder and a bottle of perpetium. The perpetium was so concentrated that I doubt there was more than 8oz in there. I had fluid at the halfway point before filling from the Colorado at Dewey. Since the start was at night, I can only say that I was never at a deficit. I probably maintained the superhydrated state or close to it up to that point. The second half was hot, but much of it was in the lasalle mtns, so cooler than in the middle of the desert. I used 6 liters plus 1x perpetium mix (all I could carry), and aprox another 2 liters plus perpetium in the second half. I was never at a deficit for water. Even with one 1/2 hour wait with no water for the iodine to do its job.

So for an 18+ hour effort, approx 13 liters 24oz of water. About 24oz per hour for a 135lb rider in the desert. Not sure if that is good or not.

A real test would be the other direction, as the heat of the day and relative altitude/water availability play a bigger role.

Sorry for a lot of information and no real summary. I haven't absorbed the whole thing yet. Somebody on here can make heads and tails of this I would bet...

Based on the research, I would expect it to work but only be useful for long events - KTR is perfect. Due to increased water storage and hence weight, performance would take a hit for shoter events. But for long, hot ones it should work well.